Republicans should have just taken yes for answer, embraced a bipartisan tax cut, declared victory and gone home for Christmas. Instead, a Republican Party that blithely voted to extend the Bush tax cuts without any offsets suddenly became very, very concerned about “paying for” a far more modest measure, and a G.O.P. that’s supposedly committed to the lowest possible middle class tax burden decided that it needed to extract concessions from a Democratic president in exchange for supporting… a middle class tax cut.